Multi-conduit, multi-nozzle fluid distributor

ABSTRACT

An apparatus for distributing a fluid is disclosed. The apparatus comprises a plurality of conduits and outlet ports that are capable of providing improved distribution of fluids. One or more conduits are arranged within a single conduit, which provides a compact and inexpensive assembly for conveying the fluids to each conduit&#39;s outlet port.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.10/198,197, filed Jul. 17, 2002 now U.S. Pat. No. 6,984,311, the entirecontents of which are hereby incorporated by reference, which is adivision of U.S. application Ser. No. 09/505,325 filed Feb. 16, 2000,now issued as U.S. Pat. No. 6,455,015 on Sep. 24, 2002, the entirecontents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to an apparatus for contacting fluids in afluid-solids contacting zone such as an adsorption zone or a reactionzone. More particularly, the invention is directed to the contacting oftwo fluids comprising a liquid phase and a vapor phase in a fluid-solidscontacting zone, and to means and methods for effecting improved heatexchange between the vapor and liquid phases in the contacting vessel.More specifically, the invention relates to a new and improved methodand apparatus for uniformly distributing a liquid phase into a flowingliquid, vapor, or mixed liquid-vapor phase in a granular or particulatesolids contacting zone, as in an adsorption tower or in a catalyticreactor such as a catalytic condensation reactor.

BACKGROUND OF THE INVENTION

Many of the most important commercial hydrocarbon conversion processesinvolve the physical or chemical treatment of hydrocarbons and otherorganic materials with beds of granular or particulate solid contactmaterials. Many of these processes involve contacting two fluids withthe contact materials. Often one of the fluids comprises a liquid phasewhile the other fluid comprises a gas or vapor phase, a liquid phase, ora mixed vapor-liquid phase. It is well known that introducing a liquidphase into either a gas or vapor phase or a mixed vapor-liquid phase,and in a manner that achieves uniform distribution, is difficult toattain.

A typical process wherein uniform distribution of liquid and gas phases,or of liquid and mixed gas-liquid phases, is necessary but infrequentlyachieved, is that of catalytic condensation. The chemical processingindustry uses the catalytic condensation process to producetransportation fuels, olefinic petrochemicals such as octene and nonene,and alkyl aromatic hydrocarbons such as cumene, that are sold in bulk ascommercial commodities. When producing transportation fuels or olefinicpetrochemicals, the catalytic condensation process oligomerizes olefinsin the presence of a particulate solid catalyst, and the process isknown within the industry as catalytic polymerization or as simply “catpoly,” with the resulting motor fuel, which may comprise dimers,trimers, and tetramers, often referred to as polymer gasoline. The feedto such a catalytic condensation reaction zone typically comprisespropylene and butylene, although propane and butane may also be present.Prevailing conditions in the reaction zone are generally vapor phase atrelatively low reaction pressures, or a dense fluid phase or a mixedvapor-liquid phase at a higher pressures. When producing alkylaromatics, the catalytic condensation process alkylates aromatichydrocarbons with olefins in the presence of a particulate solidcatalyst, and generally the reactants and products within the reactionzone are vapor-phase.

It is also well known that both the oligomerization and alkylationreactions that occur in the presence of the solid catalyst areexothermic, and that the temperature of the phase or phases in contactwith the catalyst increases due to the exothermic heat of reaction.Excessive temperatures within the catalyst bed, however, can adverselyaffect the select physical and chemical properties of the catalyst andcan lead to the formation of reaction byproducts. In order to avoidthese undesirable consequences, it is typical to arrange the catalyst ina plurality of separate fixed beds so that diluent or quench liquids maybe distributed between the beds during the reaction. In the case ofolefin oligomerization, the cool quench liquids may comprise one or moreof the olefin reactants and/or one or more paraffins having the samenumber of carbon atoms as the olefin reactants. In the case of aromaticalkylation, the cool quench may comprise one or more of each of theolefin reactants, paraffins, or aromatic reactants. The cool quenchliquids reduce the temperature of the effluent from one bed of catalystprior to feeding the mixture of effluent and quench liquid to the nextbed of catalyst.

It is typical in the art of catalytic condensation to support eachindividual bed of catalyst upon a perforated support plate or grid deck.It is also typical in the art to introduce the quench liquid between thefixed beds of catalyst by means of a single nozzle attached to a singlepipe. The quench liquid is introduced through an inlet port or openingin the reactor vessel wall into one end of the pipe, which is mounted tothe inlet port via a flanged connection on the outside wall of thereactor vessel. The pipe extends into the reactor vessel, so that thenozzle attached to the end of the pipe is at the quench point, aposition in the cross-section of the vessel where discharge of thequench liquid is desired. Typically, the quench point is at thecenter-point of the cross-section. It is typical first to assemble thepipe and nozzle assembly outside of the reactor vessel, and then toinsert, or stab in, the assembly through the inlet port. The dimensionsof the opening of the inlet port are typically only slightly greaterthan that needed to allow the pipe with its attached nozzle to passthrough. This arrangement allows the pipe and nozzle assembly to beinserted into or withdrawn from the reactor vessel even when the griddecks are in place and the beds are fully loaded with catalyst. Usingthis arrangement, assembly or disassembly of the pipe or nozzle withinthe reactor vessel does not require reactor maintenance workers to enterbetween the beds. This is an important consideration in catalyticcondensation processes, especially during loading and unloading of thecatalyst beds, when such assembly or disassembly would be difficult andtime-consuming. In fact, this consideration precludes the use incatalytic condensation reactor vessels of large distributor gridsconsisting of multiple perforated pipe branches that are positionedthroughout the entire cross-section, since such complex distributorswould require unacceptable difficulties and delays for assembly anddisassembly.

A fluid distributing apparatus in a catalytic condensation reactor isused with the intent of achieving a complete distribution of the quenchliquid as uniformly as possible throughout the cross-sectional area ofthe reactor vessel and of the catalyst bed below. It is also the purposeof the apparatus that the effluent from the catalyst bed above flowsdown from the perforated support plate throughout the cross-sectionalarea of the reactor while the quench liquids is distributed by thesingle nozzle and plate assembly throughout the cross-sectional area ofthe reactor vessel. Further, it is the purpose of fluid distributingapparatus to provide an intimate contact between the cooled quench andthe hot effluent from the bed above the fluid distributing apparatus inorder to achieve a uniform temperature of the components that are fed tothe bed below the fluid distributing apparatus.

However, the prior art fluid distributing apparatus comprising a singlenozzle attached to a single pipe has proven to be relatively ineffectivein accomplishing these objectives. Achieving these objectives is madedifficult by the fact that it is typical to add a relatively smallamount of cool quench liquids to a relatively large quantity of hoteffluent which is leaving the bed above at an elevated temperature. Thedifficulty is further complicated by the fact that the amount of coolquench is relatively small in relation to the large cross-sectional areaof the reactor vessel which must be covered in order to maintain aproper uniform distribution of the phase or phases present to the bed ofcatalyst below. In addition, the amount and composition of quenchmaterial injected after any particular bed may be varied according toneed, which depends in large part on the amount of heat of reaction tobe dissipated. For example, a recently-loaded catalyst bed containinghighly active fresh catalyst may generate a relatively large heat ofreaction, but the same catalyst bed after several months of operationmay contain partially deactivated catalyst and may generate relativelylittle heat of reaction. In order to maintain the desired inlettemperature of the catalyst bed below a catalyst bed that is generatingless heat of reaction, the flow of quench material between the twocatalyst beds must be decreased. However, experience with commercialnozzles has shown that it is typical that even only a 30% decrease inthe flow rate of quench fluid from a nozzle's design rate causes asignificant deterioration in the nozzle's capability to distribute fluidacross the cross-section of the reactor. The result is that thetemperature encountered within the catalyst bed below will be quiteuneven, and localized undesirable hot spots are often found in the bedbelow. It is well-known by those skilled in the art that the existenceof hot spots within the catalyst bed leads to indiscriminate andnonselective reactions of the reactants, which is an undesirable result.

Accordingly, an improved apparatus and an improved method for contactingfluids in a fluid-solids contacting chamber are sought that can provideuniform distribution of fluid flow, even at relatively low flow rates,so as to prevent the problems associated with high temperatures incatalyst beds.

SUMMARY OF THE INVENTION

This invention is an improved apparatus and method for contacting fluidsthat can be readily and inexpensively employed to provide uniformdistribution of fluid flow in or between particulate solid beds of afluid-solids contacting chamber, even at relatively low flow rates. Thisinvention solves the problems associated with maldistribution of fluidin such solid beds that arise from the inefficiency of nozzles whenoperated at flow rates that are significantly lower than their designflow rates. Compared to the apparatus of the prior art, the apparatus ofthis invention incorporates one or more additional conduits and outletports that are capable of providing improved fluid distribution. Theadditional conduit(s) are arranged within a single conduit, to which theadditional outlet port(s) are also attached, in a manner which allowsthe assembly of the plurality of conduits and outlet ports to beextended into the fluid-solids contacting chamber through an opening orport in the chamber wall that is, in some embodiments of this invention,either the same size or insignificantly larger than that through whichthe single conduit, with its single outlet port, is extended. Thus, theapparatus of this invention can be inserted into or withdrawn from thespace between beds of the fluids-solid contacting chamber, even whenaccess between the beds is restricted, such as when the beds are fullyloaded with solids. The method of this invention can be practiced usinginexpensive manual valves to increase or decrease the flow of fluid tothe plurality of nozzles. In addition to these advantages of lowapparatus cost and ease of operation, this invention also can increasesignificantly the time period between shutdowns of the fluid-solidscontacting chamber, thereby greatly improving the efficiency andprofitability of operating fluid-solids contacting chambers,particularly catalytic condensation reactors.

Accordingly, in an apparatus embodiment, this invention is a fluid-solidcontacting chamber. Within the chamber, which has a chamber wall, ispositioned a first bed that holds and retains particulate solids. Asecond bed which holds and retains particulate solids is also positionedwithin the chamber. Together, the chamber wall, the first bed, and thesecond bed define at least in part an interbed space that is within thechamber. The chamber also comprises an outer conduit connected to thechamber wall. A first inlet port is connected to the outer conduit forintroducing fluid into the outer conduit. A first outlet port isconnected to the outer conduit and in fluid communication with theinterbed space for discharging fluid from the outer conduit and into theinterbed space. An inner conduit is positioned within the outer conduit.The inner conduit has an inner conduit wall, and the inner conduit walland the outer conduit define at least in part an outer space. The outerspace is in fluid communication with the first inlet port and the firstoutlet port. The inner conduit wall defines at least in part an innerspace within the inner conduit. A second inlet port is connected to theinner conduit for introducing fluid into the inner conduit, and thesecond inlet port is in fluid communication with the inner space. Asecond outlet port is connected to the inner conduit and in fluidcommunication with the inner space and the interbed space fordischarging fluid from the inner space and into the interbed space.

In one of its method embodiments, this invention is a method of mixingfluids in a fluid-solid contacting chamber. An effluent is withdrawnfrom a first bed containing particulate solids in a fluid-solidcontacting chamber. The effluent passes into an interbed space withinthe chamber, and the interbed space is defined in part by the first bedand the wall of the contacting chamber. A first quench fluid passes intoan inlet end of a first quench conduit, and the first quench fluid isdischarged from an outlet end of the first quench conduit into theinterbed space at a first flow rate. After passing the first quenchfluid at the first flow rate, the flow rate of the first quench fluid isdecreased to a second flow rate that is less than the first flow rate.Also, after passing the first quench fluid at the first flow rate, asecond quench fluid passes into an inlet end of a second quench conduit,and the second quench fluid is discharged from an outlet end of thesecond quench conduit at a third flow rate that is less than the firstflow rate. The second quench fluid passes through an interconduit space,which is defined by the wall of the first quench conduit and the wall ofthe second quench conduit. After passing the second quench fluid at thethird flow rate, the flow rate of the second quench fluid is decreasedto a fourth flow rate that is less than the third flow rate. Theeffluent is contacted with at least one of the first quench fluid andthe second quench fluid in the interbed space to produce a mixture,which passes to a second bed containing particulate solids in thefluid-solid contacting chamber.

Other objectives and embodiments of the present invention are set forthin the detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a partially cut-away elevation view of a typical catalyticcondensation reactor vessel showing an embodiment of the invention.

FIG. 2 shows a flow diagram containing an embodiment of the invention.

FIGS. 3 and 4 show details of embodiments of the invention.

FIGS. 5 and 6 show further details of embodiments of the invention.

FIG. 7 shows Section A-A of FIG. 6, and FIG. 8 shows Section B-B of FIG.6.

INFORMATION DISCLOSURE

The use of a catalytic condensation process for producing cumene isdescribed at pages 1–33 to 1–36 in the book entitled Handbook ofPetroleum Refining Processes, edited by Robert A. Meyers, published byMcGraw-Hill Book Company, New York, 1986. The use of catalyticcondensation process for producing transportation fuels is describedthat pages 1–43 to 1–53 of the Meyers book.

General background information on fluid distribution, includingperforated pipe distributors, is found at pages 6–32 to 6–34 of Perry'sChemical Engineers' Handbook, Seventh Edition, edited by Robert H. Perryet al., McGraw-Hill Book Company, New York, 1997.

The use of a quench header and multiple quench nozzles for introducingquench hydrogen between fixed beds of a hydrogenation, hydrotreating,hydrocracking, or hydrodealkylation reaction zone is described in U.S.Pat. Nos. 3,652,450 and 3,652,451. These patents also describe the useof a perforated pipe grid or distributor.

U.S. Pat. Nos. 4,456,181, 5,240,183, and 5,553,783 describe spraynozzles that mix a liquid and a gas.

U.S. Pat. No. 5,081,086 describes olefin oligomerization processes andaromatic alkylation process in which it may be desirable to quench thereactants to dissipate the heat of reaction. Benefits resulting frommultiple quench injection are described.

U.S. Pat. No. 5,847,252 describes an olefin oligomerization processwherein higher molecular weight quench material is used within theoligomerization reaction zones, and higher molecular weight paraffinssuch as C₈ and heavier hydrocarbons are recycled.

DETAILED DESCRIPTION OF THE INVENTION

As noted herein above, one application wherein the present invention isuseful is in the art of catalytic condensation, that is, oligomerizingolefinic hydrocarbon constituents in a catalytic reaction zone.

FIG. 1 indicates a partially cut-away elevation view of a typicalcatalytic condensation reactor vessel wherein there is contained fourstationary or fixed beds of catalytic condensation catalyst, beds 12,14, 16, and 18. The reactor vessel comprises a vertically elongatedcontacting chamber 10, with a fluid inlet port 48 located on the top ofthe vessel and a fluid outlet port 50 located on the bottom of thevessel. Additionally, the reactor vessel contains ports 40 below each ofthe first three catalyst beds, beds 12, 14, and 16.

Each catalyst bed comprises a bed of randomly packed granular orparticulate catalyst solids. The catalytic condensation catalystcomprising each bed of particles can be of any type of catalyst known inthe art, and will typically comprised of catalyst in pilled, spherical,or extruded form. Each catalyst bed may be supported upon a layer (notshown) of nonreactive or inert particulate support material, which maybe any of the well known prior art inner support materials such that isceramic balls, Raschig rings, or Berl saddles. The top of each bed ofcatalyst may contain an additional layer (not shown) of the same type ofinert support material. As is well known to those skilled in the art, itis normal to provide such an upper layer of inert materials on top ofthe bed in order to afford improved distribution for the reactantsflowing down from the bed above before these reactants reach the activecatalyst particles. In addition, the inert support material on the topof each bed provides a layer of high density material sufficient to keepthe bed of lower density catalyst particles securely in place underconditions of pressure surge which would otherwise dislocate thecatalyst particles. Each bed of catalyst comprising catalyst particlesand any inert support material is retained and supported upon aperforated support plate or grid deck 13. Each grid deck 13 is located adistance above and away from the top 15 of the catalyst bed below. Thisprovides a confined open space 17 between each catalyst bed above andeach catalyst bed below.

Into this open space 17 there is projected from vessel port 40 andflange 39 outer quench pipe 42, which is part of pipe and nozzleassembly 20. Referring now also to FIG. 3, quench material such aspropylene, butylenes, propane, and butanes is supplied to assembly 20through two quench material supply lines 22 and 30. Quench materialsupply line 30 is capable of supplying quench material to line 34, sinceflange 32 is welded to line 30 and is connected by bolts 31 to flange33, which is welded to line 34. Line 34 in turn is attached to outerquench pipe extension 36 and can supply quench fluid into annular space25. Annular space 25 is defined in part by outer quench pipe extension36 and inner quench pipe 26. One end of extension 36 is welded to flange27, which defines the limit of that end of annular space 25. The otherend of extension 36 is welded to one side of flange 38, which is in turnconnected by bolts (not shown) to flange 39 of vessel port 40 of chamber10. In this manner, assembly 20 is mounted to chamber 10. Outer quenchpipe 42, which can be any type of pipe or other conduit device, iswelded to the other side of flange 38, and quench material can pass fromannular space 25 through flange 38 to annular space 35, which is definedin part by outer quench pipe 42 and inner quench pipe 26.

Plate 37 is attached to the end of outer quench pipe 42. Referring nowalso to FIGS. 5–8, plate 37 defines an opening 41, which permits quenchfluid to flow from annular space 35 and into fitting 47. Fitting 47 canbe any type of suitable pipe or conduit fitting, such as a pipe elbow.Fitting 47 is attached to nozzle 46 and permits quench material to flowfrom opening 41 to nozzle 46. With the longitudinal axis of outer quenchpipe 42 in a substantially horizontal orientation and the longitudinalaxis of nozzle 46 in a substantially vertical orientation, fitting 47thus redirects the quench material flow from a substantially horizontalflow direction through an angle of 90 degrees to a substantiallyvertical and upward flow direction. The tip or top of nozzle 46 definesat least one aperture 49 for discharging the quench material from nozzlein a generally vertical and upward direction. Thus, aperture 49 ispreferably arranged so as to oppose the bottom face of the bed, which issupported by plate 13. Nozzle 46 may have more than one aperture 49. Thenumber, size, arrangement, and orientation of apertures may be arrivedat without undue experimentation by a person of ordinary skill in theart of nozzle design, by considering such factors as the cross-sectionalarea of the reactor vessel which must be covered in order to maintain aproper uniform distribution of phases to the bed of catalyst 14, 16, or18 below. Other factors in nozzle selection include the design flow rateof cool quench liquid through the nozzle 46, as well as the fluidproperties of the quench liquid. Suitable nozzles includes conical spraynozzles, which are well known and are available from Bete Fog Nozzle,Inc., 50 Greenfield Street, Greenfield, Mass., USA. See, for example,U.S. Pat. No. 4,014,470. Nozzle 46 has a relatively high design flowrate.

Referring again to FIG. 3, quench material, such as propylene,butylenes, propane, and butanes, is also supplied to assembly 20 throughquench material supply line 22. Quench material supply line 22 is weldedto flange 28, which is connected by bolts 23 to flange 27. Instead of apair of flanges and bolts, a union may be used to make this connection.Supply line 22 is capable of supplying quench material into inner quenchpipe extension 24, since one end of inner quench pipe extension 24extends into line 22. Pipe extension 24, in turn, is capable ofsupplying quench material into inner quench pipe 26, since the other endof pipe extension 24 is welded to an end of inner quench pipe 26. Theouter circumference of the end of inner quench pipe 26 that is welded topipe extension 24 is welded to the inner circumference of flange 27, sothat the annular space between inner quench pipe 26 and flange 27 isblocked and thus there is a barrier to the flow of quench material fromor into annular space 25 through flange 27. Accordingly, flow of quenchmaterial through flange 27 from supply line 22 into annular space 25 isalso blocked, while the flow of quench material through flange 27, aswell as through flange 28, is capable inside pipe extension 24 and innerquench pipe 26.

Inner quench pipe 26, which can be any type of pipe or other conduitdevice, is capable of supplying quench material to fitting 45 and nozzle44. Preferably, inner quench pipe 26 is imperforate. Inner quench pipe26 extends into and through outer plate extension 36, flange 38, andouter quench pipe 42 to end plate 37. Referring again to FIGS. 5–8,plate 37 defines an opening 39, which permits quench fluid to flow frominside inner quench pipe 26 and into fitting 45. Fitting 45 and be anytype of suitable pipe or conduit fitting, such as a 90-degree pipeelbow. Fitting 45 is attached in turn to nozzle 44 and permits quenchmaterial to flow from opening 39 to nozzle 44. Elbow 45 redirects thequench material flow to a substantially vertical and upward flowdirection, and nozzle 44 discharges the quench material through aperture43. Thus, aperture 43 is preferably oriented so as to oppose the bottomface of the bed, which is supported by plate 13. The number, size,arrangement, and orientation of one or more apertures 43 defined by thetop of nozzle 44 may be arrived at without undue experimentation, aspreviously described for one or more apertures 49 of nozzle 46. In thiscase, however, one or more apertures 43 are selected with a view towardthe design flow rate of quench material through nozzle 44. Nozzle 44 hasa relatively low design flow rate compared to nozzle 46. A conical spraynozzle, described previously, is suitable for nozzle 44.

FIG. 4 shows another embodiment of assembly 20, that employs tubingrather than piping for directing quench material from quench materialsupply line 22 to plate 37 and opening 39. Accordingly, the componentparts shown in FIG. 4 are similar in function and purpose to those shownin FIG. 3, therefore FIG. 4 is not described in detail herein, in orderto avoid repetition. The item numbers used in FIG. 4 are consistent withthose used in FIG. 3. Referring now to FIG. 4, inner quench tubing 26extends from flange 27, through pipe extension 36 and pipe 42, and toplate 37. Since tubing is less rigid than pipe and will thus likely bemore flexible, FIG. 4 depicts inner quench tubing 26 as winding its waysomewhat circuitously through pipe extension 36 and pipe 42. Flange 27,fitting 45, as well as possibly extension 24, may be different fromthose used in FIG. 3 in order to accommodate the requirements ofconnections to tubing rather than pipe.

FIG. 2 shows a process flow diagram in which an embodiment of theinvention is used. For clarity and simplicity, some items associatedwith the use of the embodiment have not been shown. These include flowand pressure and temperature monitoring and control systems, vesselinternals, etc., which may be of customary design. FIG. 2 is notintended to limit the scope of the present invention as set forth in theclaims. Referring now to FIG. 2, a two-branched piping manifold isprovided for supplying quench material below each of the first threecatalyst beds, beds 12, 14, and 16. A source of quench material, such aspropylene, butylenes, propane, and butanes, flows through line 102 anddivides into two portions. A first portion flows through line 104, isregulated by manual valve 106, flows into quench material supply line30, enters assembly 20, and is ultimately discharged through nozzle 46(not shown in FIG. 2.) A second portion flows through line 108, isregulated by manual valve 110, flows into quench material supply line22, enters assembly 20, and is ultimately discharged through nozzle 44(not shown in FIG. 2).

Using the process flow diagram of FIG. 2, a wide range of quench flowrates to any bed is possible while nevertheless remaining within therange of operation for each nozzle that results in optimum distributionof fluid from that nozzle across the cross-section of the reactor. For acommercially available nozzle, the flow rate through the nozzle shouldbe maintained generally within the range of 70% to 100% of the designflow rate through the nozzle, in order to avoid significantdeterioration in the nozzle's capability to distribute fluid across thecross-section. Whether the lower end of this efficient operating rangeis, for a given nozzle, 70%, or as low as 60%, or as high as 80%, willvary from nozzle to nozzle, even within a single nozzle manufacturer'snozzle product line. Whatever the actual numerical value, this lower endof the range represents the point where the decrease in flow ratethrough the nozzle results in such an inefficient spray pattern from thenozzle that the quenching performance of the nozzle is unacceptable, asdetermined by excessive temperatures or hot spots in the catalyst bedbelow the quench point. Similarly, at the upper end of this efficientoperating range, a given nozzle's performance will become increasinglyinefficient as the flow rate through the nozzle increases to or exceedsthe design flow rate. For a given nozzle, the upper end of thisefficient operating range may be as low as, say, 95%, or as high asperhaps 120%. In any event, operating the nozzle above this upper end ofthe range exceeds the point where the increased flow rate causes aninefficient spray pattern through the nozzle, quenching suffers, andlocalized hot spots appear in the catalyst bed below the quench point.

The advantages of the apparatus and method of this invention isillustrated in the following three examples. Although theseillustrations are prophetic, they are based on experience with operatingsimilar catalytic condensation process units. These examples makereference to FIGS. 1–8. These examples are not intended to limit thescope of the invention as set forth in the claims.

EXAMPLE 1

Referring to FIGS. 1–8, nozzle 46 has a design flow rate of 100 flowunits, nozzle 44 has a design flow rate of 70 flow units, and theinitial need for quench material flow rate between beds 12 and 14 is 100flow units. Thus, valve 106 is open completely and valve 110 iscompletely closed. Over time, the need for quench flow decreases,because the catalyst in bed 12 deactivates due to nitrogen poisoning.The symptom of deactivation in bed 12 is the temperature in bed 14,which decreases over time while the flow rate of quench material throughnozzle 46 is constant. When bed 14 temperatures falls to an unacceptableextent, valve 106 is closed slightly. This decreases the flow or quenchmaterial and thereby allows the temperatures in bed 14 to increase tothe desired temperature for bed 14.

Over time, valve 106 continues to be closed to a greater and greaterextent in response to more severe deactivation of the catalyst in bed12. After a period of time, valve 106 is closed to the point where theflow rate through nozzle 46 is 70 flow units, or 70% of its design flowrate. For purposes of this illustration, it is assumed that 70% of thedesign flow rate of nozzle 46 is the point at which the quenchingperformance of nozzle 46 becomes so inefficient as to be unacceptable.Even though over time the temperatures in bed 14 are decreasing, therebydecreasing the need for quench flow through nozzle 46, high localizedtemperatures in bed 14 indicate that the performance of nozzle 46 hasbecome inefficient. That is, despite the general decline over time oftemperatures in bed 14, nevertheless the diminished performance ofnozzle 46 at low quench flow rates means that nozzle 46 is unable toprevent excessively high temperatures from arising in localized spotswithin the bed 14.

At this point in time, in the absence of the present inventive apparatusand method, the excessively high temperatures would tend to causeunacceptable amounts of polymerized by-products to form, the presence ofthese by-products in beds 14, 16, and 18 would cause the pressure dropsacross these beds to increase excessively, and for that reasonprocessing in chamber 10 would need to be stopped prematurely andchamber 10 would need to be taken out of service and decommissioned, sothat the deactivated catalyst in bed 12 could be replaced. Although intheory only bed 12 would have to be unloaded and replaced, the practicein industry is to unload not only bed 12 but also beds 14, 16, and 18 aswell, even if, as is nearly always the case, the catalyst in those otherbeds is not excessively deactivated. Thus, without the presentinvention, chamber 10 and the catalyst within it are used inefficiently,since chamber 10 is taken out of service and all of its catalyst isdiscarded, despite its having useful life remaining.

In accord with the apparatus and method of the present invention,however, chamber 10 remains in service. Valve 106 is completely closed,and valve 110 is completely opened, and this changeover is preferablyperformed simultaneously and in synchronization. Preferably, as the flowthrough nozzle 46 is being decreased, the flow through nozzle 44 isbeing increased. Although preferably this change does not substantiallyalter the flow rate of quench material through assembly 20, orpreferably the flow rate after the changeover is not more than the flowrate prior to the changeover, the quench material flow is redirectedfrom nozzle 46 to nozzle 44, which at 70 flow units, now operates at100% of its design flow rate. Therefore, there is an improvement in theflow distribution of the quench material between beds 12 and 14, andthis eliminates the excessively high localized temperatures within bed14. Therefore, chamber 10 continues in operation, and the delays andcosts associated with prematurely shutting down chamber 10 are avoided.While chamber 10 remains in operation, the catalyst in beds 14, 16, and18 continue to be used to process hydrocarbons, which in effect extendsthe useful life of the catalyst in these beds relative to theprematurely shortened life that this catalyst would have had in theabsence of this invention. Meanwhile, the catalyst in bed 12 continuesto deactivate, and in response, valve 110 is closed slightly. Over time,valve 110 continues to be closed as catalyst deactivation in bed 12worsens. After a period of time, valve 110 is closed to the point wherethe flow rate through nozzle 44 is 49 flow units, or 70% of its designflow rate. For purposes of this illustration, it is assumed that 70% ofthe design flow rate of nozzle 44 is the point at which the quenchingperformance of nozzle 44 becomes so inefficient as to be unacceptable.Therefore, at this point, chamber 10 is finally shut down. But, theapparatus and method of this invention lengthen the time betweenshutdowns of chamber 10 and utilize the catalyst in chamber 10 moreefficiently, thereby increasing the efficiency and decreasing the costsassociated with operating chamber 10.

EXAMPLE 2

Example 2 illustrates the apparatus and method of this inventionproviding quench material to chamber 10 over a similar period of time asthat covered in Example 1. However, the focus of this Example 2 is onproviding quench between beds 16 and 18, rather than between beds 12 and14 as in Example 1. All references to valves, nozzles, and quench flowsin this Example 2 are thus to those for the assembly 20 between beds 16and 18, rather than to those associated with the assembly 20 betweenbeds 12 and 14 in the case of Example 1.

Referring then to the assembly 20 between beds 16 and 18, nozzle 46 hasa design flow rate of 100 flow units and nozzle 44 has a design flowrate of 70 flow units. For purposes of this illustration, it is assumedthat, for each of nozzles 44 and 46, 70% of the design flow rate of thenozzle is the point at which the quenching performance of the nozzlebecomes so inefficient as to be unacceptable. The initial need forquench material flow between beds 16 and 18 is 50 flow units, which isrelatively low. Such a low need for quench material arises because thecatalyst in bed 12 is highly active and most of the olefinic feedstockoligomerizes in bed 12. Thus, the amount of unreacted olefin that passesnot only through bed 12 but also through bed 14 to enter bed 16 isrelatively low, and the need to quench the effluent of bed 16 isminimal. At this time, valve 110 is partially closed, so as to allowonly 50 flow units of quench material to flow through nozzle 44. Notethat 50 flow units through valve 110 corresponds to slightly more than70% of the design flow rate of nozzle 44. Valve 106 is completelyclosed. If, instead of valve 110, valve 106 were opened and operated at70% of its design rate, the resulting flow of 70 flow units of quenchmaterial would unacceptably decrease the temperatures in bed 18, since aflow of only 50 flow units is needed.

Over time, the need for quench flow between beds 16 and 18 increases,because the catalyst in bed 12 deactivates due to nitrogen poisoning andmore and more olefins pass unreacted through beds 12 and 14 and enterbed 16. The symptom of increasing utilization of the catalyst in bed 16is the temperature in bed 18, which increases over time while the flowrate of quench material through nozzle 44 is constant. When bed 18temperatures rises to an unacceptable extent, valve 110 is openedslightly more. This increases the flow or quench material and therebyallows the temperatures in bed 18 to decrease to the desired temperaturefor bed 18.

Over time, valve 110 continues to be opened to a greater and greaterextent in response to more olefin oligomerization using the catalyst inbed 18. After a period of time, valve 110 is opened to the point wherethe flow rate through nozzle 44 is 70 flow units, or 100% of its designflow rate. For purposes of this illustration, it is assumed that 100% ofthe design flow rate of the nozzle 44 is the point at which thequenching performance of the nozzle becomes so inefficient as to beunacceptable. If the flow rate through nozzle 44 was further increasedin response to the temperatures in bed 18, high localized temperaturesin bed 18 would arise, since the performance of nozzle 44 has becomeinefficient. That is, at flow rates over 100% of its design flow rate,the diminished performance of nozzle 44 at such high quench flow ratesmeans that nozzle 44 is unable to prevent excessively high temperaturesfrom arising in localized spots within the bed 18.

At this point in time, in the absence of the present inventive apparatusand method, processing in chamber 10 would need to be stopped andchamber 10 would need to be taken out of service and decommissioned, sothat the deactivated catalyst in bed 12 could be replaced. Although intheory only bed 12 would have to be unloaded and replaced, the practicein industry, as mentioned in Example 1, is to unload not only bed 12 butalso beds 14, 16, and 18 as well. Thus, without the present invention,chamber 10 and especially the catalyst within bed 18 is usedinefficiently, since chamber 10 is taken out of service and all of itscatalyst is discarded, despite the catalyst in bed 18 having much of itsuseful life remaining.

In accord with the apparatus and method of the present invention,however, chamber 10 remains in service. Valve 110 is completely closed,and valve 106 is opened slightly, so that the flow through nozzle 46 is70 units of flow. This changeover is preferably performed simultaneouslyand in synchronization. Preferably, while the flow through nozzle 44 isbeing decreased, the flow through nozzle 46 is being increased. Althoughpreferably this change does not substantially alter the flow rate ofquench material through assembly 20, or preferably the flow rate afterthe changeover is not less than the flow rate prior to the changeover,the quench material flow is redirected from nozzle 44 to nozzle 46,which at 70 flow units, now operates at 70% of its design flow rate.Therefore, there is an improvement in the flow distribution of thequench material between beds 16 and 18, and this eliminates theexcessively high localized temperatures within bed 18. Therefore,chamber 10 continues in operation, and the delays and costs associatedwith prematurely shutting down chamber 10 are avoided. While chamber 10remains in operation, the catalyst in beds 12, 14, 16, and especially 18continue to be used to process hydrocarbons, which in effect extends theuseful life of the catalyst in these beds relative to the prematurelyshortened life that this catalyst would have had in the absence of thisinvention. Meanwhile, the catalyst in bed 12 and possibly bed 14continues to deactivate, more olefin oligomerization occurs in bed 16,and in response, valve 106 is opened slightly. Over time, valve 106continues to be opened as catalyst deactivation in bed 12 worsens andmore olefins oligomerize in bed 16. After a period of time, valve 106 isopen to the point where the flow rate through nozzle 46 is 100 flowunits, or 100% of its design flow rate. For purposes of thisillustration, it is assumed that 100% of the design flow rate of nozzle46 is the point at which the quenching performance of nozzle 46 becomesso inefficient as to be acceptable. Therefore, at this point, chamber 10is finally shut down. But, the apparatus and method of this inventionlengthen the time between shutdowns of chamber 10 and utilize thecatalyst in chamber 10 more efficiently, thereby increasing theefficiency and decreasing the costs associated with operating chamber10.

EXAMPLE 3

Example 3 illustrates another embodiment of this invention where themanual valves 106 and 110 shown in FIG. 2 are replaced with flowregulating or control valves. As used herein, a flow regulating valve isa valve in which the extent of opening of the valve is automaticallycontrolled by a pneumatic or electrical signal from a control station,which is usually located in a centralized control facility, such as acontrol room or control building. Compared to a manual valve, theposition of which is adjusted by hand turning or manipulation of ahandle on the valve itself, the position of a regulating valve can becontrolled more precisely and more frequently. With a regulating orcontrol valve, accurate and frequent adjustments to the valve positionare possible to an extent that would be excessively time-consuming ortedious for an operator to attempt by hand turning of a manual valve.Consequently, a flow regulating valve permits flow rates to becontinually optimized in response to desirable flow control objectivesthat would be impractical or impossible with a manual valve. Suitableflow regulating valves are well known to persons of ordinary skill inthe chemical processing industry.

Of course, in Examples 1 or 2, flow regulating or control valves couldhave been used instead of manual valves. It is believed, however, that,given the costs associated with such valves, most operators of catalyticcondensation process units would generally use manual valves whenoperating in the manner described in Examples 1 or 2.

In this Example 3, replacing manual valves 106 and 110 shown in FIG. 2with flow regulating or control valves allows the operator of acatalytic condensation process unit to operate over a significantlywider range of optimum quench flow rates, for a given nozzle and pipeassembly 20. Although there is a cost incurred with installing the flowregulating valves, that expense may be justified in some cases, sincethe flow regulating valves can significantly lengthen the time betweenshutdowns of the chamber 10. The resulting increase in on-streamutilization of chamber 10 can significantly improve the profits andeconomics of operating a catalytic condensation process.

In this Example 3, the design total flow rate of quench material to bothnozzles (i.e., nozzles 44 and 46) is 100 flow units. Nozzle 44 has adesign flow rate of 37 flow units, and nozzle 46 has a design flow rateof 63 flow units. Regulating valve 110 is capable of controlling theflow to nozzle 44 either at 0% (i.e., no flow) or between 70% and 100%of its design flow. Therefore, the actual flow rate through nozzle 44 iseither 0 (i.e., no flow) or is between 25.9 and 37 flow units.Similarly, regulating valve 106 is capable of controlling the flow tonozzle 46 either at 0% or between 70% and 100% of its design flow. Thus,the actual flow rate through nozzle 46 is either 0 (i.e., no flow) or isfrom 44.1 to 63 flow units. Using flow regulating valves, it is possibleto independently control each of the actual flow rates at these flowrates. Thus, quench material can flow solely through nozzle 44, solelythrough nozzle 46, or simultaneously through nozzles 44 and 46. Whenquench material is flowing through both nozzles, it is believed that theinterference in the spray patterns of the two nozzles will causeminimal, if any, impairment in fluid distribution, and may improvedistribution through the cross-section by virtue of the turbulencecreated by the colliding spray patterns.

In this embodiment, the entire range from 25.9 to 100 flow units ofquench flow rates to any bed is attainable, with two small exceptions,in the following manner. First, with no flow through nozzle 46, the flowthrough nozzle 44 can be regulated between 25.9 and 37 flow units. Then,with no flow through nozzle 44, the flow through nozzle 46 can beregulated between 44.1 and 63 flow units. Next, with the flow throughnozzle 46 at 44.1 flow units, the flow through nozzle 44 can beregulated between 25.9 and 37 flow units, corresponding to a total flowof 70 to 81.1 flow units. Finally, with the flow through nozzle 44 at 37flow units, the flow through nozzle 46 can be regulated between 44.1 and63 flow units, for a total flow of 81.1 to 100 flow units. Thus, the twosmall exceptions are from 37.1 to 44.0 flow units and from 63.1 to 69.9flow units, which should not impair operating flexibility significantly,allowing for relatively minor adjustments in feed rate or quenchtemperature, if needed. Therefore, this Example 3 shows that theapparatus and method of the present invention allows the amount ofquench material injected after any particular bed to be varied accordingto need over essentially the entire range from as low as nearly 25% ofthe design rate up 100% of the design rate.

By comparison, if the prior art arrangement comprising a single pipe anda single nozzle had been used, the amount of quench material injectedwould have been limited to the range of only from 70% to 100% of thedesign rate. Thus, Example 3 is clearly advantageous over the prior artarrangement. But, Example 3 also provides a striking advantage overExamples 1 and 2. In Examples 1 and 2, the lowest quench flow rate wasabout 49% of the design flow rate, but this Example 3 allows the quenchflow rate to reduced to about 25% of the design flow rate. Thus, even incomparison to Examples 1 and 2, this Example 3 allows significantly evenlonger periods of time between shutdowns of chamber 10, greaterutilization of the catalyst in beds 14, 16, and 18, and a large increasein operating flexibility.

In general, for the apparatus and method of this invention, it will beapparent to those skilled in the art that the relative design flow ratesof the two nozzles 44 and 46 can vary with the specific application. InExample 3, for instance, the design flow rate of nozzle 44 is 37% of thesum of the design flow rates for nozzles 44 and 46, and the design flowrate of nozzle 46 is 63% of the sum of the design flow rates for nozzles44 and 46. The design flow rates of each nozzle may be equal, i.e. 50%of the sum of the design flow rates for the two nozzles. In order tohave a wider operating range of flow rates, it is preferred that thedesign flow rate of one nozzle be larger than the design flow rate ofthe other nozzle. The design flow rate of one nozzle is generally fromabout 5% to about 49%, preferably from about 20 to about 45%, and morepreferably from about 30 to about 41%, of the sum of the design flowrates of the two nozzles. Accordingly, the design flow rate of the othernozzle is generally from about 51% to about 95%, preferably from about55 to about 80%, and more preferably from about 59 to about 70%, of thesum of the design flow rates of the two nozzles.

It will also be apparent to those skilled in the art that, where thedesign flow rates of the two nozzles are different, then it will besuitable for the cross-sectional area in the assembly 20 for flow ofquench material to the nozzle having the higher design rate to begreater than the cross-sectional area for flow of quench material to thenozzle having the lower design flow rate. Thus, the cross-sectional areaof the annular space 35, which provides quench material to nozzle 46, isgreater than the cross-sectional area within inner quench pipe 26.Furthermore, it is not a requirement of the present invention that thequench material flowing to the high design rate nozzle 46 must flowthrough the annular space 35 while the quench material flowing to thelow design rate nozzle 44 must flow through the inner quench pipe 26.Accordingly, as an alternative to the embodiments shown in the Figures,for an outer quench pipe of a given inside diameter, a larger-diameterinner quench pipe 26 may be used, thereby increasing the cross-sectionalarea available for flow through the inner quench pipe 26 and decreasingthe cross-sectional area available for flow through the annular space35. Thus, it will be apparent to those of ordinary skill in the art thatthe inner quench pipe 26 could supply quench material to a nozzle havinga higher design rate than that of the nozzle to which quench material issupplied via annular space 35.

The dimensions for the inventive contacting chamber and its elements, inparticular its conduits and its nozzles, cannot be set forth herein withgreat specificity, since a great many factors will affect the dimensionswhich are required and any specific application. Among the factors toconsider in a catalytic condensation reactor, for example, are the rateof flow of the effluent from the catalyst bed above to the bed below,and the rate of flow of the quench material. The vapor-liquiddistribution of the effluent flowing from the bed above will also affectthe dimensions which are required in the design of the conduits andnozzles, and the temperature and pressure of the effluent will have apronounced effect upon this vapor-liquid distribution. In addition, itmust be realized that the temperature at which the quench material isintroduced via a vessel port 40 will also have a pronounced effect onthe degree of quench which is experienced and on the spray affect whichis produced. Finally, molecular weights must be considered, and thedensity and viscosity of the various liquid and vapor phases is ofprimary consideration. However, for purposes of illustration of theapplication of this invention in a cylindrical, vertically orientedchamber, it may be set forth typical relative positions of the nozzlesand the center point of a horizontally-positioned substantially circularbottom face of a catalyst bed in such a chamber. If the substantiallycircular face has a center point and a radius R, then the distancebetween the center point and the vertical projection from theaperture(s) of any nozzle to the center point of the face is generallyless than 10%, and preferably less than 5%, of the radius R.

It will also be apparent to those skilled in the art that this inventionin is not limited to only a single pipe and nozzle assembly 20 below anyparticular bed. That is, multiple assemblies 20, each mounted to avessel port 40, may extend into open space 17 between beds 12 and 14.For example, four assemblies may extend into open space 17, with eachassembly's nozzle optimally positioned to cover one-fourth of thecross-section of the bed face, so that all four nozzles cover the entirecross-section of the bed face. Where more than one assembly extends intosuch an open space below a horizontally-positioned circular bottom faceof a catalyst bed in a cylindrical, vertically oriented chamber, thedistance between the center point of the face and the verticalprojection from the aperture(s) of any nozzle to the center point of theface may be greater than 10% of the face radius R.

This invention is also not limited to only one inner quench pipe 26within the outer quench pipe 42. Depending on the cross-sectional areasof annular spaces 25 and 35, one more additional inner quench pipes orinner quench tubing lengths may be accommodated, for a total of two ormore inner quench pipes or inner quench tube lengths. Each additionalinner quench pipe or tubing would have, at the end that is extendedtoward end plate 37, a corresponding opening in plate 37, and would beattached via its corresponding fitting to a individual nozzle. In thisway, additional nozzles could be incorporated into a single assembly 20and thus into space 17. The additional inner quench pipe or tubing couldextend through outer quench pipe 42 and into outer quench pipe extension36. From there, the other end of each additional inner quench pipe ortubing could be routed through an opening which could be provided in thewall of the outer quench pipe extension 36, and connected a quenchsupply line. Alternatively, the additional inner quench pipe or tubingcould be routed within an existing inner quench pipe or tubing, so thatnot only is the existing inner quench pipe or tubing in an annulararrangement with respect to the outer quench pipe and outer quench pipeextension, but the additional inner quench pipe or tubing is in anannular arrangement with respect to the existing inner quench pipe ortubing.

Preferably, each such additional nozzle added would be smaller in designflow rate than any of the existing nozzles. Obviously, this ispreferable from the viewpoint of being able to fit the additional nozzleand its fitting within the limited space on the end plate 36 and to fitthe inner quench pipe within the confined annular spaces 25 and 35. Inaddition, this is preferable from the point of view of widening therange of quench flow rates provided by a given nozzle and pipingassembly 20. For example, if the range of operation of the largestnozzle is from 70% to 100% of the design rate of flow of quench materialbetween two beds, and the range of operation of the second-largestnozzle is from 49% to 70% of that design flow rate, then the purpose foradding any third nozzle would be to have a range of operation from 49%and below, in particular from 34.3% to 49% of that design flow rate.Thus, the third nozzle would be the smallest of the three nozzles. Itwill be apparent to those skilled in the art that this examplepresupposes that each of these three nozzles has a range of operation offrom 70% to 100% of its design flow, since for the second largest nozzle70% of 70% is 49%, and for the third nozzle 70% of 49% is 34.3%. When anozzle has a range of operation of from 70% to 100% of its design flow,the flow rate at 100% of its design flow is 143% of the flow rate at 70%of its design flow, since 100 divided by 70 is 1.43. Those skilled inthe art are able to compute the corresponding percentages for any nozzlethat has a range of operation relative to its design flow rate that isother than from 70% to 100%.

It will also be noted that quench material entering assembly 20 viaquench material supply line 30 may have a different composition from thequench material entering assembly 20 via quench material supply line 22.That is, in contrast to the embodiment shown in FIG. 2 wherein a commonsupply line 102 is capable of delivering quench material of a singlecomposition to both lines 104 and 108, an alternative embodiment wouldbe capable of supplying quench material of a different composition froma separate and independent source to line 108, while line 102 wouldcontinue to be capable of supplying quench material to line 104. In thisembodiment, there would be no connection fluid communication betweenline 102 and line 108. Such an embodiment would be useful if it wasdesired to be able to pass a quench fluid having one composition to thechamber when the need for quench material is great and only the nozzlehaving the high design rate is in use, while also being capable ofpassing a quench material having a different composition to the chamberwhen the need for quench material is small and only the nozzle havingthe low design rate is in use.

The apparatus and method of this invention are useful in olefinoligomerization, aromatic alkylation, and other types of hydrocarbonconversion processes where solid catalysts have been known to be useful.In olefin oligomerization, the source of the olefin input stream istypically a light gas stream recovered from the gas separation sectionof a fluid catalytic cracking (FCC) process. Other sources for suitableolefin feeds will also include C₄ streams from steam cracking and cokeroff gas. The olefin feed stream is characterized by having an overall C₄olefin concentration of at least 10 wt %. In most operations, thisolefin feed stream will contain C₄ olefins but it may also constituteall or substantial quantities of C₃ olefins. Typically the olefin feedscan have a C₃ to C₅ olefin concentration of at least 30 wt %. Preferredfeeds will have a C₄ olefin concentration of at least 30 wt % and morepreferably at least 50 wt %. Preferably the olefin feed stream willcomprise at least 20 wt % and more preferably 30 wt % isobutene. Theisobutene will preferably comprise at least 33% of the total butenes.The olefin content of preferred feeds will predominately comprisebranched olefins with isobutene present in large quantities. Thereaction of normal pentenes and propylene is promoted by maintaining ahigh concentration of isobutene in the feed to the oligomerization zoneof this invention. Oligomerization of pentene and propylene into highoctane isomers is promoted by having an olefin distribution in the feedto the isomerization zone that comprises at least 50 wt % isobutene.When large quantities of propylene are present in the feed to theoligomerization zone, the octane number of the product may be increasedby raising the percentage of isobutene in the butene fraction of thefeed. Preferably the butene fraction will comprise 65% isobutene whenlarge amounts of propylene enter the oligomerization zone.

Suitable oligomerization zones for this invention take on many forms.The oligomerization process is known by many names such as catalyticcondensation and also catalytic polymerization. Known catalysts foreffecting such reactions include heterogeneous catalysts such as Yzeolites, beta zeolites, silicalite, and sulfonated resins, as well ashomogenous catalysts such as boron trifluoride, as described in U.S.Pat. Nos. 3,906,053; 3,916,019 and 3,981,941.

The preferred catalyst for the oligomerization process is a solidphosphoric acid (SPA) catalyst. The SPA catalyst refers to a solidcatalyst that contains as a principal ingredient an acid of phosphoroussuch as ortho-, pyro-, or tetra-phosphoric acid. The catalyst isnormally formed by mixing the acid of phosphorous with a siliceous solidcarrier to form a wet paste. This paste may be calcined and then crushedto yield catalyst particles, and the paste may be extruded or pelletedprior to calcining to produce more uniform catalyst particles. Thecarrier is preferably a naturally occurring porous silica-containingmaterial such as kieselguhr, kaolin, infusorial earth, and diatomaceousearth. A minor amount of various additives such as mineral talc,fuller's earth, and iron compounds including iron oxide may be added tothe carrier to increase its strength and hardness. The combination ofthe carrier and the additives preferably comprises about 15–30% of thecatalyst, with the remainder being the phosphoric acid. The additive maycomprise about 3–20% of the total carrier material. Variations from thissuch as a lower phosphoric acid content are however possible. Furtherdetails as to the composition and production of SPA catalysts may beobtained from U.S. Pat. Nos. 3,050,472; 3,050,473; 3,132,109; 4,912,279;4,946,815; 5,043,509; 5,059,737; and 5,081,086; and from otherreferences.

Oligomerization zones in general are maintained at conditions which mayvary widely depending on the olefins undergoing reaction and the desiredproduct. Operating conditions also depend on the specific catalystcomposition that is employed. Operating conditions may be suitable formaintaining vapor phase, liquid phase, or mixed vapor-liquid phaseoperation. The oligomerization reaction zone may be also be operated attemperatures and pressures that increase compatibility with conditionsof upstream processes that provide the oligomerization feedstocks or ofdownstream processes that use the oligomerization effluent. A broadrange of suitable pressures is from about 15 psi(g) to about 1200 psi(g)(103 to 8274 kPa(g)). The introduction of C₈ and heavier paraffins intothe oligomerization reaction zone has been found in some cases toimprove selectivity of the oligomerization reaction zone to C₈ olefinproduction. In a preferred embodiment of the method of this invention,an SPA catalyst is utilized in a chamber-type reactor to form aneffluent containing C₅ through C₁₂ hydrocarbons having boiling pointswithin a gasoline boiling point range of about 100° F. to about 450° F.(38 to 232° C.) as determined by the appropriate ASTM distillationmethod. The preferred temperature of the oligomerization reaction zonewill typically be in a range of from 200 to 500° F. (93 to 260° C.) andwill more typically be in a range of from 300 to 450° F. (149 to 232°C.). Pressures within the oligomerization reaction zone will usually bein a range of from 200 to 1200 psi(g) (1378 to 8274 kPa(g)) and moretypically in a range of from 400 to 1000 psi(g) (2758 to 6895 kPa(g)).Steam or water may be fed into the reactor to maintain the desired watercontent in the catalyst.

The catalyst is preferably disposed in fixed beds within theoligomerization zone in what is known as a chamber-type reactorstructure. In a chamber-type reactor, the reactants flow through aseries of large diameter catalyst beds. The temperature of the reactantsmay be controlled by passing relatively inert hydrocarbons which act asa heat sink, and isobutane in the oligomerization feedstock supplies alarge proportion of the inert hydrocarbons that act as the heat sink.However, in accord with the apparatus and method of this invention,temperature control within the oligomerization reaction zone is alsopromoted by the use of a quench material. A quench material thatcomprises the inert materials and C₈ and heavier paraffins may be usedsimultaneously for temperature control. The quench material serves asits primary advantage of the control of temperatures within theoligomerization reaction zone. As a secondary purpose, the quenchmaterial can provide a flushing function to inhibit the development ofcoke and the deactivation of coke in the deactivation of the catalystwithin the reaction zones. As pressure within the oligomerizationreaction zone decreases the flushing function of the quench materialdecreases as the vaporization of the reactants and quench within thereaction zone increase. The use of higher molecular weight quenchmaterial within the oligomerization reaction zones to inhibit cokingwhile permitting lower pressure operation is one possible method for theoperation of this invention. Thus, the addition of heavier quenchmaterials facilitates the operation of the oligomerization zone athigher temperatures and lower pressures while still flushing thecatalyst and preventing coke production. The passing of higher molecularweight paraffins, such as C₈ and heavier hydrocarbons, can also improveselectivity of the oligomerization zone to produce the desired C₇+olefin products. Since the higher molecular weight materials havebenefits beyond use as a quench, it can be beneficial to add all or aportion of such material to the inlet of oligomerization reactor withthe feed.

The different catalyst beds are preferably contained within one or morecylindrical, vertically oriented vessels and the feed stream preferablyenters the top of the reactor. The olefins then are passed downwardlythrough the chamber and its beds. Typically, a chamber-type reactor willcontain about five catalyst beds.

With the addition of the olefin input stream the combined feed to theoligomerization zone will preferably have a ratio of paraffins toolefins of from 1:1 to 5:1. Typically the paraffin concentration of thefeed to the oligomerization reaction zone will be at least 50 wt % andmore typically at least 70 wt %. A high percentage of the olefins in thefeed stream entering the process as the secondary feed stream upstreamare reacted in the oligomerization reaction zone along with theisobutene with olefin conversions in the range of from 80 to 99%. Theprincipal oligomerization products comprise C₇+ olefins.

When used to effect alkylation of aromatic hydrocarbons with analkylating agent, the alkylating agent may be selected from a group ofdiverse materials including monoolefins, diolefins, polyolefins,acetylenic hydrocarbons, and also alkylhalides, alcohols, ethers,esters, the latter including alkylsulfates, alkylphosphates, and variousesters of carboxylic acids. The preferred olefin-acting compounds areolefinic hydrocarbons which comprise monoolefins containing one doublebond per molecule. Monoolefins which may be used as olefin-actingcompounds in the method of the present invention are either normallygaseous or normally liquid and include ethylene, propylene, 1-butene,2-butene, isobutene, and the higher molecular weight normally liquidolefins such as the various pentenes, hexenes, heptenes, octenes, andmixtures thereof, and still higher molecular weight liquid olefins, thelatter including various olefins polymers having from about 9 to about18 carbon atoms per molecule including propylene trimer, propylenetetramer, propylene pentamer, etc. Cycloolefins such as cyclopentene,methylcyclopentene, cyclohexene, methylcyclohexene, etc., may also beutilized, although not necessarily with equivalent results. Otherhydrocarbons such as paraffins, naphthenes, and the like containing 2 to18 carbon atoms may also be present in the alkylating agent. Forcatalyzing aromatics production, it is preferred that the monoolefincontains at least 2 and not more than 14 carbon atoms. Morespecifically, it is preferred that the monoolefin is propylene.

The aromatics substrate which is charged to the alkylation reaction zonein admixture with the alkylating agent may be selected from a group ofaromatics compounds which include individually and in admixture, benzeneand monocyclic alkyl-substituted benzene of from 7 to 12 carbon atomshaving the structure of a phenyl group to which is attached from 1 to 5groups selected from a methyl group, an ethyl group, or a combinationthereof. In other words, the aromatics substrate portion of thefeedstock may be benzene, an alkylaromatic containing from 1 to 5 methyland/or ethyl group substantial ends, and mixtures thereof. Non-limitingexamples of such feedstock compounds include benzene, toluene, xylene,ethylbenzene, mesitylene (1,3,5-trimethylbenzene) and mixtures thereof.It is especially preferred that the aromatics substrate is benzene.

Known catalysts for effecting such reactions include heterogeneouscatalysts such as Y zeolites, beta zeolites, ZSM-5, PSH-3, MCM-22,MCM-36, MCM-49, and MCM-56. Suitable catalysts also include the zeolitebeta disclosed in U.S. Pat. No. 5,723,710, and solid phosphoric acid(SPA) catalyst described hereinabove.

Generally, the alkylation zone is maintained at conditions which mayvary over a wide range based on the desired reactants, products, andcatalyst. Temperatures which are typical for use in the method of thisinvention are those temperatures which initiate a reaction between anaromatic substrate and the particular olefin used to selectively producethe desired monoalkylaromatic compound. Temperatures suitable for useare generally from about 212 to about 734° F. (100 to 390° C.),especially from about 302 to about 527° F. (150 to 275° C.). Pressuressuitable for use in the method of this invention are preferably aboveabout 14.7 psi(g) (101 kPa(g)), but should not be in excess of about1900 (13100 kPa(g)). An especially desirable pressure range is fromabout 147 to about 588 psi(g) (1014 to 4054 kPa(g)). The liquid hourlyspace velocity (LHSV) based upon the feed rate of the aromatic feedstockis generally from about 0.5 to about 50 hr⁻¹, and especially form about1 to about 10 hr⁻¹. Although the operating conditions may be suitablefor maintaining vapor phase, or mixed vapor-liquid phase operation, thetemperature and pressure combination used is typically such that thealkylation reaction takes place in essentially the liquid phase. In aliquid phase process for producing alkylaromatics, the catalyst iscontinuously washed with reactants, thus preventing buildup of cokeprecursors on the catalyst. This results in reduced amounts of carbonforming on the catalyst. This, in turn, extends catalyst cycle life ascompared to a gas phase alkylation process, in which coke formation andcatalyst deactivation can be a major problem. A regulated amount ofwater or steam may be added to the alkylation reaction zone in order tomaintain the desired water content of the catalyst.

The catalyst within the alkylation zone is preferably disposed in fixedbeds in a chamber-type reactor structure, as described previously forolefin oligomerization, in which the reactants flow through a series oflarge diameter catalyst beds. In a continuous process for alkylatingaromatic hydrocarbons with olefins, the previously described reactantsare continuously fed into the chamber-type reactor containing thecatalyst. The feed admixture may be introduced into the alkylationreaction zone containing the alkylation catalyst at a constant rate, oralternatively, at a variable rate. Normally, the aromatic substrate andolefinic alkylating agent are contacted at a molar ratio of from about1:1 to about 20:1 and preferably from about 2:1 to about 8:1. Thepreferred molar feed ratios help to maximize the catalyst life cycle byminimizing the deactivation of the catalyst by coke and heavy materialdeposition upon the catalyst. The alkylation reaction system may containone or more multi-bed chamber-type reactors in serious. Although thefeed to the reaction zone can flow vertically downwards through thecatalyst in a typical plug-flow reactor or horizontally across thecatalyst in a radial-flow reactor, it is typical for the feed to flowvertically upward through the catalyst bed in a plug-flow reactor.

In order to maintain the reaction temperature in the preferred range andthus reduce the formation of unwanted polyalkylaromatics, if it isdesirable to quench the reactants to dissipate the heat of reaction. Inalkylation, a quench stream comprised of the alkylating agent olefin,the alkylating agent or a portion of the reactor effluent stream, ormixtures thereof, is injected into the alkylation reactor system inorder to dissipate heat and supply additional amounts of olefinalkylating agent and unreacted aromatic substrate at various locationswithin the reaction zone. This is accomplished, for example, in asingle-stage reactor by multiple injection of the aforementioned quenchstream components into the reaction zone via strategically placed inletlines leading into the reaction zone. The amount and composition ofquench material injected into either a single stage reaction system or amulti-stage reaction system may be varied according to need. Benefitsresulting from multiple quench injection include eliminating costlycooling apparatus, providing for a larger heat sink, optimizing themolar ratio of olefin-to-aromatic throughout the reaction zone, andimproving selectivity to the desired alkylaromatic product.

The different catalyst beds are preferably contained within one or morecylindrical, vertically oriented vessels and the aromatic feed streampreferably enters the top of the reactor. The olefinic feed stream istypically divided into as many portions as there are catalyst beds, withone portion being injected above each bed. Each olefin portion is thusmixed either with the reactor feed or with a bed effluent, and theresulting mixture passes downwardly to the bed below the point ofmixing. Typically, a chamber-type reactor will contain about two to fourcatalyst beds.

A substantial portion of the aromatic substrate hydrocarbon andessentially all of the olefin alkylating agent react in the alkylationreaction zone in the presence of the catalyst to form monoalkylaromaticcompounds and polyalkylaromatic compounds. The preferred products of thealkylation process using the apparatus and method of this inventioninclude cumene (isopropylbenzene) and ethylbenzene.

While the embodiments disclosed here in above have been directed to theexothermic catalytic reactions of olefins oligomerization and aromaticsalkylation, the apparatus and method of the invention is not so limited.Those skilled in the art will perceive that the method of contacting twofluids in a fluid-solids contacting chamber and the apparatus thereforhave equal application in any fluid-solids contacting zone, such as forthe exothermic catalytic reaction of hydrocarbons in a hydrogenatmosphere and as in adsorption zones. Additionally, the apparatus isnot limited to the injection between fixed beds of particulate contactsolids, but it can also find application as the feed distributionapparatus at the top of the first bed contained within the contactingchamber. The method and apparatus also is not limited to the specificfluids discussed hereinabove. Thus, the first fluid passed downwardlythrough the bed above may be solely a liquid phase, solely a vaporphase, or a mixture of liquid phase and gas phase. Furthermore, thesecond fluid or third fluid flowing upward from the pipe and nozzleassembly need not be a low temperature fluid quenching a highertemperature down-flowing first fluid, but either may be at the sametemperature as the first fluid, or may be at a temperature above thefirst fluid temperature in order to provide a heat input into thefluid-solids contacting zone.

1. A chamber comprising a fluid distributor comprising: a) ahorizontally positioned outer conduit; b) a first inlet port connectedto said outer conduit for introducing fluid into said outer conduit; c)a first outlet port connected to said outer conduit for dischargingfluid from said outer conduit; d) an inner conduit positionedhorizontally and coaxially within said outer conduit, wherein said innerconduit has an inner conduit wall, wherein said inner conduit wall andsaid outer conduit define at least in part an annular space, whereinsaid annular space is in fluid communication with said first inlet portand said first outlet port, and wherein said inner conduit wall definesat least in part an inner space within said inner conduit; e) a secondinlet port connected to said inner conduit for introducing fluid intosaid inner conduit, wherein said second inlet port is in fluidcommunication with said inner space; and f) a second outlet portconnected to said inner conduit and in fluid communication with saidinner space for discharging fluid from said inner space, furthercharacterized in that the area of the cross-section of said annularspace, wherein the cross-section of said annular space is perpendicularto the longitudinal axis of said annular space, is greater than the areaof the cross-section of said inner space, wherein the cross-section ofsaid inner space is perpendicular to the longitudinal axis of said innerspace.